Electron gun assembly and method of assembling the gun



Aug. 16, 1966 DRAKE 3,267,316

ELECTRON GUN ASSEMBLY AND METHOD OF ASSEMBLING THE GUN Filed Dec. 26. 1961 INVENTOR Oscar A. Drake ir Maw ATTORNEY United States Patent 3,267,316 ELECTRON GUN ASSEMBLY AND METHOD OF ASSEMBLING THE GUN Oscar A. Drake, Seneca Falls, N.Y., assignor to Sylvanra Electric Products Inc., a corporation of Delaware Filed Dec. 26, 1961, Ser. No. 162,040 6 Claims. (Cl. 31382) This invention relates to electron guns and in particular to the alignment and spacing of grids forming part of the gun structure of a cathode ray tube.

In a conventional form. of gun utilized in image reproduction devices such as cathode ray tubes, there are a number of control and accelerating electrodes arranged longitudinally of the gun with apertures in the electrodes in alignment. To obtain good control, definition, and brightness of the image on the tube screen, it is important, particularly as to the electrodes closest to the cathode, to position them a proper distance a-prt. Grids designated as the number 1 and number 2 grids, closest to the cathode, are provided with small apertures of the order of .040 inch in diameter or less and, for optimum results, these openings should be in perfect alignment.

In the prior art, the electrodes including the number 1 and number 2 grids were fastened in alignment to elongated glass rods through the intermediary of pins or stirrups welded to the electrodes and fused into the rods. The stirrups were preliminarily welded to the electrodes and the fusing of the ends of the pins or stirrups into the glass rods was effected in a jig. However, particularly with reference to the number 1 and number 2 grids, aperture alignment could not be effected in a facile manner. The apertures of the grids in themselves, as stated heretofore, are small and the tolerance in the size of the apertures is of the order of .001 inch. Therefore, it can be seen that extreme care would have to be exercised to secure alignment of these apertures in the grids and this cannot readily be obtained when all of the electrodes are fastened to the rods at the same time.

Accordingly, it is an object of this invention to facilitate improved grid aperture alignment and grid spacing in an electron gun.

A further object is to simplify and improve electron I gun fabrication.

In accordance with one aspect of this invention, the gun accelerating anodes and the number 2 grid are secured to the supporting insulating rods in any conventional fashion. Also secured to the same supporting rods is a flanged collar larger in internal diameter than the outside diameter of the number 1 grid, the flange of this collar or protrusion being adapted to have secured thereto a second flanged collar or protrusion of smaller diameter fixedly secured to the exterior of the number 1 grid. Adjusting the second collar laterally with respect to the first collar enables alignment of the apertures in the grids to be effected, and when these apertures are aligned, the collars may be permanently secured together. Since the cathode is normally incorporated into the number 1 grid structure, it may be inserted within this grid and affixed thereto either before or after the alignment procedure.

For a better understanding of the present invention, together with other and further objects, advantages, and capabilities thereof, reference is made to the following disclosure and appended claims in connection with the accompanying drawings in which:

FIG. 1 shows a partially sectioned plan view of a fragmentary portion of an electron gun of the type adapted for use in cathode ray tubes;

FIG. 2 is a perspective view of a collar used in the assembly of FIG. 1 and which is adapted to be mounted in the insulating supports;

3,267,316 Patented August 16, 1966 "ice there is disclosed a fragmentary portion of an electron gun comprising a first grid 10, a second grid 12, and a first anode 14. The cathode (not shown) which is inserted and afiixed within the first grid may be of a conventional type. The other electrodes may also be of the type normally employed in cathode ray tubes.

The second grid 12 and anode 14 are each provided with double pronged stirrups 16 welded or otherwise secured to the electrodes. The prongs have their free ends fused into or otherwise secured to insulating rods 18 made of glass or the like. Additionally mounted by the rods 18 is a flanged collar 20 which may be fused into the glass rods. The electrodes 12 and 14 and the collar 20 may be secured to the glass rods in a jig so as to establish appropriate spacing between them and preferably with the longitudinal axis of the collar coincident with the longitudinal axis of the grid 12. If desired, the collar may be provided with pins or stirrups for mounting in rods 18 rather than using a large collar flange for embedment in the rods.

A second flanged collar 22 is Welded to or otherwise fastened to the cylindrical wall of grid 10 with the top surface of the flange at a predetermined distance from the top level of the grid 10 in order to establish a predetermined distance between the first grid 10 and the second grid 12 when the flange of collar 22 is fastened to the flange of collar 20. Collar 22 may be attached to collar 20 by any suitable means such as welding or brazing.

Each grid has a transverse wall with a perforation therein. For the purpose of illustrating the invention, the grids are disclosed as substantially cup shaped with grid 10 having an apertured wall 24 and grid 12 with an apertured bottom wall 26. The apertures are designated, respectively, as 28 and 30. In the completed gun, the aperture 28 in grid 10 is opposite the emissive material of the cathode, which is contained within grid 10 but not shown, and this aperture is of the order of .025 inch. For optimum results, this aperture must be in alignment with the aperture 30 in the grid 12, the line through the apertures preferably being coincident with the longitudinal axes of the grids. The aperture 30 may be of the same dimension as or slightly larger or smaller than the dimension of the aperture 28 in grid 10. In order to facilitate securing the alignment of apertures in the grids, the internal diameter of the collar 20 is made larger than the external diameter of grid 10 and the collar 20 is mounted in the glass rods 18 in a position relative to the grid 12 to permit considerable lateral shifting of the grid 10 in the collar 20. The flange of collar 22 is made smaller than the space between the rods, or recessed in the areas adjacent the rods, to permit the collar and aflixed grid 10 to shift laterally. In the assembly of grid 10 to the gun, the flange of collar 22 is butted against the flange of collar 20, and the collar 22 and afiixed grid 10 moved laterally until the apertures 28 and 30 in the grids 10 and 12 are aligned. Such alignment may be ascertained visually by sighting along the axis of the gun, or suitable instrumentalities may be inserted into the grids to assure exact alignment of the apertures. For example, a shouldered rod, the end of which is diametered to correspond with the diameters of the apertures in the grids, may be used.

After the grids and 12 are aligned the two flanges of the collars are secured to each other, as by brazing or welding. After this mounting operation, the gun is completed by adding the other parts conventionally associated with the structure.

While a flanged collar has been described in conjunction with the placement of the number 1 grid, this invention contemplates locating and positioning any or all of the apertured gun elements normally affixed to the glass rod alignment supports of the gun structure by the same means.

Other types of collars or supports may be used with the gun electrodes to effect alignment. For instance, shelftype supports 29 may be used with grid 10 as shown in FIG. 4, or a ledge 32 may be formed as an integral part of grid 10 as illustrated in FIG. 6. Also, other structures such as support 30 of FIG. 5 may be substituted for collar 20.

While there have been shown and described what are at present considered the preferred embodiments of the invention, it will be obvious to those skilled in the art that various changes and modifications may be made therein without departing from the scope of the invention as defined by the appended claims.

What is claimed is:

1. In an electron gun, first and second grids, each grid being substantially in the form of a cup with apertured bottom, the first cup shaped grid being inverted with its bottom uppermost, a first collar having an internal diameter larger than the external diameter of the first grid, a second collar embracing the first grid and secured thereto, said second collar being diametrically smaller than said first collar to facilitate lateral movement thereon, supports fixedly positioning the second grid and first collar with reference to each other, and means securing said second collar to said first collar to achieve alignment of the apertures in the bottoms of the cup shaped grids. I

2. In an electron gun, insulating support rods, an electrode secured to said support rods, said electrode having a transverse wall with a small aperture therein, a collar secured to the rods in spaced relation to the electrode, a second electrode having a transverse wall with a small aperture therein, support means rigidly secured to said second electrode, said support means being of a size to facilitate lateral movement on said collar, said second electrode having an external diameter smaller than the internal diameter of the collar, and means securing said support means to said collar to achieve alignment of said apertures in the transverse walls of said electrodes.

3. In an electron gun, support rods, a first grid, a second grid, and a pair of collars, said second grid and a first one of the collars being secured to said support rods in longitudinally spaced relationship and said second grid 'being in the form of a cup with a substantially centrally apertured bottom, the first grid being in the form of a cup with the bottom uppermost and also apertured substantially centrally of its bottom, the external diameter of the first grid being smaller than the internal diameter of said first one of said collars, said second collar embracing said first grid and fastened thereto with freedom of lateral movement of the second collar between the rods when said collars are unattached to one another to facilitate alignment of the apertures, and means securing the two collars to each other with the apertures of the two grids in the alignment and parallel to the axis of the grids.

4. In an electron gun, the combination comprising insulating support rods, a first electrode secured to said support rods, said electrode having a transverse wall with a small aperture therein, a collar secured to the rods in spaced relation to said electrode, a second electrode having a transverse wall with a small aperture therein, said second electrode having a preformed circular ledge of a diametrical size smaller than said collar to facilitate lateral movement thereon, said second electrode having an external diameter smaller than the internal diameter of said collar and means securing said circular ledge on the second electrode to said collar with the first and second electrode apertures in alignment.

5. The method of assembling apertured electrodes of an electron gun comprising mounting a first one of the apertured electrodes in a support, mounting a first collar on said same support in spaced relation to the first electrode, securing a second apertured electrode within a second collar, said second apertured electrode having external dimensions smaller than the internal dimensions of the first collar, bringing the two collars into a superjacent position shifting the second collar laterally relative to the first collar to effect registration of the apertures in the two electrodes, and securing the two collars to each other with the apertures in said registration.

6. The method of assembling apertured electrodes of an electron gun comprising mounting a first one of the apertured electrodes in a support, mounting a collar on said support in spaced relation to the first electrode, positioning a second apertured electrode having a preformed circular ledge relative to said first electrode to bring said collar and said electrode ledge into a superjacent relationship, said second apertured electrode having external dimensions smaller than the internal dimensions of the collar, shifting said circular ledge lateral-1y relative to the collar to effect registration of the apertures in the two electrodes, and securing the two collars to each other with the apertures in said registration.

References Cited by the Examiner UNITED STATES PATENTS 2,909,689 10/1959 Case 31382.l 2,947,897 8/1960 Rodriguez et a1. 3l3254 X HERMAN KARL SAALBACH, Primary Examiner.

GEORGE N. WESTBY, Examiner.

S. CHATMON, JR., Assistant Examiner. 

1. IN AN ELECTRON GUN, FIRST AND SECOND GRIDS, EACH GRID BEING SUBSTANTIALLY IN THE FORM OF A CUP WITH APERTURED BOTTOM, THE FIRST CUP SHAPED GRID BEING INVERTED WITH ITS BOTTOM UPPERMOST, A FIRST COLLAR HAVING AN INTERNAL DIAMETER LARGER THAN THE EXTERNAL DIAMETER OF THE FIRST GRID, A SECOND COLLAR EMBRACING THE FIRST GRID AND SECURED THERETO, SAID SECOND COLLAR BEING DIAMETRICALLY SMALLER THAN SAID FIRST COLLAR TO FACILITATE LATERAL MOVEMENT THEREON, SUPPORTS FIXEDLY POSITIONING THE SECOND GRID AND FIRST COLLAR WITH REFERENCE TO EACH OTHER, AND MEANS SECURING SAID SECOND COLLAR TO SAID FIRST COLLAR TO ACHIEVE ALIGNMENT OF THE APERTURES IN THE BOTTOMS OF THE CUP SHAPED GRIDS. 